4BT engine vibration or tameing the schrew.

[Steve Graham]

I had this idea to reduce the vibration coming from my 4Bt in my Scout for some time. I'm using the factory type isolator for the 6B's (92Dodge Diesel) for my 4B, their way to stiff for a unbalanced 4B like mine but there cheap and readily availably. So I thought why not drill a couple of holes to reduce the stiffness. OK but how do you measure the results. The pan of water isn't very scientific but it's all I could come up with and it works. I now have objective data to say that two 3/8 holes drilled in the isolator will reduce the vibration. Some what. The pan is 8" in dia. The water is hard Arizona water. The pan is old. like me and the Scout. Maybe next week I'll try cross drilling the mounts. . Here's the link to the photos

Steve

http://cards.webshots.com/cp-80181859-oXBF-album/145330871qGCbOn

 

[rbalcom]

Have you considered a seperate subframe mounting like early 4 banger mercedes diesels?



i'm trying to design a seperate subframe under my 4bta... i'll try the pan of water test to confirm results and let you know... . you can also stack your side engine mounts and probably achieve the same thing except for the torque wind up... maybe that is why mercedes used a driveline rubber doughnut ... . thanks for sharing test results!

 

[Steve Graham]

Originally posted by rbalcom

Have you considered a seperate subframe mounting like early 4 banger mercedes diesels?

cut... ...

i... . thanks for sharing test results!

Did not know of the subframe on the Mercedes, know of any pictures?



Steve

 

[LAlessi]

i dont know why, but mine does not vibrate offensively. matter of fact the clatter is more offensive than the vibration. i just dont notice it.....

 

[SAvery]

Hey Lee, I would bet it's because your vehicle has the extra 2000 lbs to dissipate vibration. Maybe not the reason, but I bet it could help.

 

[LAlessi]

hmmm, good point. never even thought of that...

 

[Steve Graham]

Lee,

Arin't you using the smaller 4B isolators not the 6B isolators?



Steve

 

[LAlessi]

i use the stock dodge mounts for 89-91 6bt, i think. i use the mounts that the p-30 frito truck used. i THINK they are dodge 6bt mounts.....

 

[driverswanted]

pan and water

What kind of food is stuck to the edge of the pan? I'm getting hungry. Are you going to drill more holes? I was thinking of maybe doing about six to eight holes that size on the aftermarket NAPA version of that mount.

 

[Steve Graham]

I have just over 2 weeks of driving with the "drilled" mounts and I don't believe that any more hole are needed. The only perceptible vibration is at idle now. The outside mirrors shake at idle but clear up at speed. I used to get a numbing vibration holding on to the steering wheel, now that is gone. It's really amazing what's achieved with the 2 holes!



Steve

 

[driverswanted]

Thanks Steve,



That's good to know. I'll be trying the same here shortly.